In God's word (the Holy Bible), the Lord calls Satan the god of this world (the Earth). Satan is a very powerful being. God has allowed him to act with great influence and power here, along with the other angels that followed with him in rebellion, of whom we now call devils/demons/fallen angels.
"The name "god" is here given to him, not because he has any divine attributes, but because he actually has the homage of the people of this world as their god, as the being who is really worshipped, or who has the affections of their hearts in the same way as it is given to idols. By "this world" is meant the wicked world; or the mass of people. He has dominion over the world. They obey his will; they execute his plans; they further his purposes, and they are his obedient subjects. He has subdued the world to himself, and was really adored in the place of the true God" -Barnes commentary on 2 Corinthians 4:4
There is a spiritual plane that exists directly over our physical. Psychedelics & other mind altering drugs are a way to partially access this spiritual dimension & the spirits (demons) there.
In the original greek texts the word that we translate to witchcraft or sorcery is "pharmakeia", defined "properly, drug-related sorcery, like the practice of magical-arts". Pharmakeia being derived from the same word pharmacy. Using mind altering drugs to access the spiritual might be considered by God to be doing witchcraft even if your not trying to contact spirits or do any nefarious activities. Regardless if God considers it witchraft or not, He doesn't want us doing these things.
Now not all drugs are bad. Using an ibuprofen for a headache from time to time is fine but using drugs to access the spiritual plane or interact with spirits is not okay.
Don't listen to these new age spiritual teachers sent from Satan to get you to try to seek spiritual knowledge through psychedelics or other mind altering substances. Neither give heed to their many other teachings that will lead you down the false path to Hell. Jesus Christ is the only way and all your spiritual needs can be found in the Holy Bible and through the guidance of the Holy Spirit.
Yes you can experience part of the spiritual plane through psychedelics but the experience is controlled by Satan and demons and doing so is sinful. The demons will often times give you a "bad trip". Christians must wait for the Lord to return to experience the spiritual, safely, and with a good conscience toward God.